The Home Office insisted it had “verified” the ages of all the refugees and that all of those who were brought to the UK were aged between 14 and 17.

The youngsters arrive by coach at Lunar House, the head office of UK Visas and Immigration, in Croydon, south LondonCredit:
Nick Edwards for The Telegraph

However, Conservative MPs warned that photographs of the refugees suggested that many of the group were older than 17.

Home Office documents show that if a refugee does not have a birth certificate, a Home Office screening officer can certify them as a child based on their “physical appearance” or “demeanour”.

The document states that refugees “should be treated as an adult if their physical appearance/demeanour very strongly suggests that they are significantly over 18 years of age”.

However, it says that “all other applicants should be afforded the benefit of the doubt and treated as children”.

The guide for Home Office officials adds: “All available sources of relevant information and evidence should be considered, since no single assessment technique, or combination of techniques, is likely to determine the applicant’s age with precision.”

David Davies , the Conservative MP for Monmouth, said: “These don't look like ‘children’ to me. I hope British hospitality is not being abused.”

An aerial view of the Jungle camp in Calais in August, when it was home to more than 9,000 migrantsCredit:
PHILIPPE HUGUEN/AFP

He added: “These young men don't look like minors to me. They are hulking teenagers who look older than 18. I'm all for helping the genuine children but the well of goodwill is rapidly being exhausted here.

"I'm also curious that there are no young women - I would have thought they would be much more vulnerable. I worry that once again British hospitality is being abused.

“There is no way of knowing if someone is a child. We could end up causing even more misery if we are not careful. We should invite anyone who wants to come to the UK to take dental tests.”

Refugee kids to be rescued from Calais' Jungle. Many have the right to come to UK but are stuck due to bureaucracy https://t.co/QKoYYIZXzq

Documentation supplied by the Red Cross on the issue of bringing child refugees to the UK features pictures children who appear to be under the age of ten and toddlers.

A Home Office spokesman said: “We can confirm a group of children who left the Calais camp this morning have arrived in the UK.

“This is the start of the process to transfer as many eligible children as possible before the start of the clearance, as the Home Secretary set out in Parliament.

“These vulnerable children, aged between 14 and 17, were transferred to the UK under the care of Home Office staff, with the support of volunteers from specialist NGOs and charities. They will join their families in the UK as quickly as possible over the coming days.”

The Home Office said that “essential checks have been made on these young people for their safety and the safety of others” and added: “This means verifying their ages, confirming their identities and eligibility to come to the UK and running security checks.”

Dozens more children are expected to arrive this week after a team of British officials were sent to Calais to help French authorities speed up the transfer of minors ahead of the dismantling of the Jungle.